[PATCH] D59687: [DebugInfo] Prologue inserter need to insert DW_OP_deref_size

[Markus Lavin via Phabricator via llvm-commits]

markus created this revision.
markus added reviewers: aprantl, dblaikie.
markus added a project: debug-info.
Herald added subscribers: ormris, jdoerfert.
Herald added a project: LLVM.

The `PrologEpilogInserter` need to insert a `DW_OP_deref_size` before prepending a memory location expression to an already implicit expression to avoid having the existing expression act on the memory address instead of the value behind it.

The reason for using `DW_OP_deref_size` and not plain `DW_OP_deref` is that big-endian targets need to read the right size as simply truncating a larger read would yield the wrong result (LSB bytes are not at the lower address).


Repository:
  rL LLVM

https://reviews.llvm.org/D59687

Files:
  lib/CodeGen/AsmPrinter/DwarfExpression.cpp
  lib/CodeGen/MIRParser/MIParser.cpp
  lib/CodeGen/PrologEpilogInserter.cpp
  lib/IR/DebugInfoMetadata.cpp
  test/CodeGen/X86/prologepilog_deref_size.mir

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